It was revealed on Strong Heart that Super Junior's Heechul once made idol turned actress Park Soo Jin cry. Park Soo Jin shared a story about when she used to act with Heechul in Loving You A Thousand Times. Park Soo Jin said, "I am really close with Heechul. We were like siblings because we got along so well while acting. He's a very tidy person." She continued, "Once, we were acting out a scene when he suddenly grabbed my hand to check for how clean my nails were. When he saw that they were dirty, he told me he couldn't act because he wasn't able to show emotion for someone like me." She then said, "I was going to just move on by saying sorry but he kept looking mad." With her mood a little down, Heechul continued to tease her by singing "dirt dirt dirt" while they were filming for a scene inside a car. She eventually shed tears but I think Heechul was just kidding.